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The potential of three externally applied chemical plant activators, Bion, BABA and methyl jasmonate, known to act only through the plant defence system and not on the pathogen directly, to induce resistance against wild-type Pectobacterium carotovorum was examined in white-flowered calla lily ( Zantedeschia aethiopica ). Following a 24-h induction period, plants were challenge-inoculated with P. carotovorum , originally isolated from calla lily or potato plants, previously transformed using a gfp broad-host-range promoter-probe vector. After another 24 h, Bion treatment (10 µ g mL−1 , as a drench) reduced disease symptoms more than sixfold and bacterial proliferation by four orders of magnitude. BABA treatment (5–10 µ g mL−1 , also as a drench) reduced the rate of infection by 75–85%. However, the protection afforded by both inducers did not persist. Also, at higher concentrations both displayed a phytotoxic effect. By contrast, methyl jasmonate (10 m m , applied as a leaf spray) completely inhibited P. carotovorum development in calla lily leaves and afforded a long-lasting effect. It is suggested that the defence response of calla lily against P. carotovorum involves the SA-signalling pathway in the short term, but the jasmonate/ethylene-signalling pathway is required for durable protection. 相似文献
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Any Mary Petri?an Burghard von Lüpke Ion Catalin Petri?an 《European Journal of Forest Research》2009,128(1):61-74
In a field study, we measured saplings of beech, ash and maple growing in a fairly even-aged mixed-species thicket established
by natural regeneration beneath a patchy shelterwood canopy with 3–60% of above canopy radiation reaching the saplings. Under
low light conditions, maple and ash showed a slight lead in recent annual length increment compared with beech. With increasing
light, ash and maple constantly gained superiority in length increment, whereas beech approached an asymptotic value above
35% light. A suite of architectural and leaf morphological attributes indicated a more pronounced ability of beech to adapt
to shade than ash and maple. Beech displayed its leaves along the entire tree height (with a concentration in the middle crown),
yielding a higher live crown ratio than ash and maple. It allocated biomass preferentially to radial growth which resulted
in low height to diameter ratios, and expressed marked plagiotropic growth in shade indicating a horizontal light-foraging
strategy. In addition, beech exhibited the highest specific leaf area, a greater total leaf area per unit tree height, a slightly
greater leaf area index, and a greater plasticity to light in total leaf area. Ash and maple presented a “gap species” growth
strategy, characterized by a marked and constant response in growth rates to increasing light and an inability to strongly
reduce their growth rates in deep shade. In shade, they showed some plasticity in displaying most of their leaf area at the
top of the crown to minimize self-shading and to enhance light interception. Through this, particularly, maple developed an
“umbrella” like crown. These species-specific responses may be used for controlling the development of mixed-species regeneration
in shelterwood systems. 相似文献
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Gianina Popescu-Pelin Carmen Ristoscu Liviu Duta Iuliana Pasuk George E. Stan Miruna Silvia Stan Marcela Popa Mariana C. Chifiriuc Claudiu Hapenciuc Faik N. Oktar Anca Nicarel Ion N. Mihailescu 《Marine drugs》2020,18(12)
We report on new biomaterials with promising bone and cartilage regeneration potential, from sustainable, cheap resources of fish origin. Thin films were fabricated from fish bone-derived bi-phasic calcium phosphate targets via pulsed laser deposition with a KrF * excimer laser source (λ = 248 nm, τFWHM ≤ 25 ns). Targets and deposited nanostructures were characterized by SEM and XRD, as well as by Energy Dispersive X-ray (EDX) and FTIR spectroscopy. Films were next assessed in vitro by dedicated cytocompatibility and antimicrobial assays. Films were Ca-deficient and contained a significant fraction of β-tricalcium phosphate apart from hydroxyapatite, which could contribute to an increased solubility and an improved biocompatibility for bone regeneration applications. The deposited structures were biocompatible as confirmed by the lack of cytotoxicity on human gingival fibroblast cells, making them promising for fast osseointegration implants. Pulsed laser deposition (PLD) coatings inhibited the microbial adhesion and/or the subsequent biofilm development. A persistent protection against bacterial colonization (Escherichia coli) was demonstrated for at least 72 h, probably due to the release of the native trace elements (i.e., Na, Mg, Si, and/or S) from fish bones. Progress is therefore expected in the realm of multifunctional thin film biomaterials, combining antimicrobial, anti-inflammatory, and regenerative properties for advanced implant coatings and nosocomial infections prevention applications. 相似文献
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Kinetic studies of lycopene isomerization in a tributyrin model system at gastric pH 总被引：1，自引：0，他引：1
A semi-preparative HPLC method was developed in order to isolate and purify the 13-cis-lycopene isomer in tomato-based materials. The result was compared with the naturally predominant all-trans-lycopene isomer, in terms of stability to gastric pH at physiological temperature in a tributyrin model system. Kinetic experiments confirmed that lycopene isomerization is a reversible reaction, and under these conditions the all-trans isomer is more stable than the 13-cis isomer. In addition, it was found that at gastric pH 13-cis-lycopene would predominantly isomerize to the all-trans form rather than undergo oxidation/breakdown. A simulation based on the rate constants calculated in the kinetic study indicated that at gastric pH the lycopene isomeric distribution aimed toward an equilibrium characterized by approx 16% 13-cis-, 16% 9-cis-, and 68% all-trans-lycopene. This study suggests that pH-driven isomerization in the stomach is at least partially responsible for the relatively high cis-lycopene proportion found in vivo. 相似文献